A preferred embodiment of the present invention relates to a material particularly for the prevention of bedsores.
Various means such as creams, pads and soft materials have been used to try to prevent the formation of bedsores. However, none of these means has proven to be truly efficient.
One well-known method also involves using polymer gel-based plates, such as silicone gel or hydrogel-based plates, to protect skin or for load distribution. For example, to ensure a load distribution function, one well-known method involves using a plate made of a relatively hard silicone gel of PDMS (polydimethylsiloxane) type. Patent No. FR2712487 describes a silicone gel having properties similar to those of the footpad for the prevention of pathologies caused by hyper pressure appearing essentially on or under the feet.
However, the formation of bedsores results from stresses exerted on the tissues that differ from hyper pressures. FIGS. 1 and 2 schematically represent in a cross-section an area of skin and tissues 1 around a bone 2 bearing on a rigid surface 10. In FIG. 1, the bone 2 is separated from the rigid surface 10 by a layer of tissues of minimum thickness 1. The pressure exerted on the rigid surface leads to the formation of a stress field represented in shading 3, the grey level of which is representative of the intensity of the stresses. The darkest area located between the bone 2 and the rigid surface delimits the area in which the bearing stresses are the highest.
The tissues are therefore more compressed in line with the bone 2, and less and less compressed moving away from the bone.
In reality, the pressure of a bone is not necessarily perpendicular to the bearing surface. The phenomena occurring in this situation are shown by FIG. 2. The stress F exerted by the bone comprises a vertical component Fv and a horizontal component Fh. The vertical component can create hyper pressure and form an area 5 reducing the thickness of the skin on one side of the bone. The reduction induces poor irrigation of the tissues in this area. The horizontal component Fh induces a shear stress Fa and compression stress Fc in the tissues on either side of the bone 2, which tend to put strain on the tissues particularly due to friction on the bearing surface 10. The vessels also undergo these stresses. The skin and the deeper tissues are thus poorly irrigated due to the compression, and undergo alternate stresses parallel to the bearing surface the effects of which are all the more negative when the tissues are less elastic as is the case in elderly people or malnourished people. On the surface of the skin, this friction can also lead to the formation of lesions. The compression, shear and friction stresses thus tend to form a bedsore.
It is therefore desirable to develop a material to be placed between the skin and the bearing surface which enables the negative effects of pressure and friction on the skin to be removed, or at least reduced.
Patent application WO 02/17840 describes a dressing intended particularly for the treatment of bedsores. The dressing is made of an extensible, flexible textile material, which holds in place on the injured area of the body a pad made of a molded silicone polymer gel and having a Shore A hardness from 6 to 8. It transpires that this pad does not prevent the formation of bedsores.